In general, the power source (e.g., black wire from the panel) goes to the common side of the dual switch, and the other two (switched) sides go to the appliances' hot sides. The appliances share the neutral. As Frenchie points out, the topology is slightly different if the power comes from the panel to the switchbox or the fan's box, but a few minutes spent with a pencil and the back of an old envelope will be well spent to get the picture of what's going on.

I can't follow your wiring, but by hooking the white to the switch, it in effect became a black, red, or blue wire, not a white one. You still need to find a source for a white neutral wire to the fixture. And that is assuming the "black" wire is actually connected to a "hot" wire.

Since you "just hooked it up to the switch", I assume there were only two wires going from the fan box to the switch box -- probably a black/white pair. Another black/white pair should have brought power from the panel to the fan box. The black wire from the panel (the "hot" wire) should have carried current via the black wire to the switch, where it was switched on and off to the white wire (which should have been marked with black paint or tape). Back in the fan box, the white wire from the panel (the "neutral") should have been connected to one of the fan wires, and the white wire from the switch box (which also should have been marked with black paint or tape) should have been connected to the other fan wire. The complete circuit is then hot from the panel, through the switch, through the fan, and return to the panel via the neutral.

Now we introduce the double switch. If you look at the switch terminals, one side of the switch will have two black screws in 2 brass strips connected by a small tab, the other side will have two brass screws in two separate brass strips, each obviously associated with one of the individual switches. The black wire from the fan box should be connected to one of the black screws, and the white wire (which should have been marked with black paint or tape) should be connected to one of the screws on the other side of the switch. Notice that the black ("hot") wire from the fan box is now actually feeding both switches, via the little tab connecting the two halves of the brass strip -- the 2nd switch is all dressed up with no place to go, i.e., nothing's connected to it.

Now to connect the light, you've somehow got to get a wire from the other separate screw on the switch to one side of the light, and the other side of the light to the white neutral wire from the panel in the fan box. How you do this is up to you, but in new construction I'd run a three-wire cable from the fan box to the switchbox (one "hot", 2 switched) and another 2-wire cable from the fan box to the light box (one switched, one neutral).

Draw some pictures and it might make sense. Of course if any of my initial assumptions is wrong, none of this works. If that's the case, do what Frenchie suggested and draw us a picture, or describe what's going on in all 3 boxes (fan, switch, and light) in detail.

Okay, I just studied your description a bit. I think you can make all this work by disconnecting your existing light-to-switch white wire at both ends. Then connect another white wire (the white wire in a two-wire cable works OK) from the light to the white wire from the panel in the fan box. Logically, we're moving the end of the light-to-switch white wire from the switch to the system neutral.

That description is not much better than the original one. He is probably already using the "white wire in the romex" for the switched lead to the fixture, and what does he do with it once he disconnects both ends? But he probably does need another white wire for the neutral, we just don't know how he is going to run it.

WIthout being there and measuring things, it is hard to say, but this is my guess.

At the fan, there's two cables coming into it; one from the power panel, the other going to the switch. The white wire coming from the power panel is connected directly to the fan. The black wire from the panel is jumpered to the other wire that is going to the switch. It goes down to the switch, and when the switch is closed, it comes back to the fan on the white, which is connected to the black wire to the fan, providing it with power. BTW, this wire is supposed to be labled with a red marker to indicate that it is a switched hot lead, but is ignored way too often.

So, you need to verify this, and you need to continue the white wire from the power panel to the white wire of the new light. Then, with the new lead from those lights to the new switch, at the switch for the fan, connect both black leads together with a couple of pigtails, and then go to each of the switches, providing power to both items when their respective switches are closed. Leave the white wires where they are, but mark them with red tape or a red magic marker.

The grounds need to run all the way through each item, but I left that out.

If you don't own one, you need either at the minimum a test lamp, or a meter.

I'd run a three-wire cable from the fan box to the switchbox (one "hot", 2 switched) and another 2-wire cable from the fan box to the light box (one switched, one neutral).

Click to expand...

You were doing so well - but that "one hot 2 switched" is wrong - it'd be one hot, one switched, and one neutral. Like HJ said, what Lee's probably missing is a neutral for the light circuit. Assuming that by wiring in the attic, he means the power enters there...

By the way, ALL of you are wrong about the white wire marked as hot. If you re-designate a white, it can't be the switch leg returning to the light, it has to be the constant "always hot" wire.

here's the best i can tell... power came from the basement panel..up the wall to the ceiling to a junction box... then it split... to the fan... and then back down the wall to the original switch.. there, a pair of wires was attached to the switch..

everything worked well.

then i took out the single switch and attached the fan to the top switch.. fan works great..

then i put the can in the ceiling and ran romex from it down to the other switch.

Please allow some patience for my ignorance.. I will take a Sunday break... and thank everone for their help...

i'll let you know next week, where I am ..... even with A/C ,,,it seems to hot to work today...

Those two wires down to the switch are both "hot" when the fan is on. You do not have a white neutral to the light, so it cannot work. If the black wire is the switched leg, then the white one is "hot" which can be more confusing, and dangerous to a DIY person. I would rather have him confused by the wiring than in the emergency room because he touched a "safe" white wire. And if it happened to me, I would be looking for the idiot that wired it that way.

I said "one hot, two switched", and that is in fact the situation, although I would have been wrong about the colors. Having read through the Code (God, I wish they had had an English major on the team that wrote the damned thing) and the JLC thread, I now see that my "one hot" would be the reidentified white conductor (coming from the black in the light outlet and going to the common switch terminal), and the "two switched" would be the black and red conductors (coming off the switched terminals and returning to the fan and light) in a "standard" 14-3 cable.

Someday I'll figure out how to draw pictures for this forum and save a hell of a lot of words.

If the 2 screws on the "hot side" of your switch is still connected by the little tab, it only needs one black wire connected to it - the one bringing power to the switch. If the tab's been broken off and thay are completely independant, then you need to pigtail that black, and connect to both screws.

Making sense, yet?

The other black, that goes to the light, is now a switch leg - like the red is for the fan - it goes on the OTHER side.

...if this still isn't making sense to you, I really think you should call in a pro.